Joint design of user power allocation and relay beamforming in two-way MIMO relay networks

This paper is concerned with the joint optimization of user power allocation and distributed relay beamforming in two-way wireless relay networks in which multiple multi-antenna relays assist multiple single-antenna users. The design aims at maximizing the minimum information rate among user pairs subject to various practical power constraints at the users and relays. Since the nonconvex structure of the problem is highly complicated, the existing approaches to relax the design problem into a convex program do not appear to be applicable. To solve this challenging nonconvex optimization problem, we introduce auxiliary variables and cast the design problem into a d.c.(difference of convex functions) program. Then, we develop an efficient iterative algorithm of sequential convex optimization to obtain the optimized solutions. Extensive simulation results demonstrate that our proposed joint design outperforms the only relay beamforming design.